<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <!-- 样式 -->
    <style>
        button{
            background-color: pink;
            font-size: 16px;
        }
    </style>
</head>
<body>
    <!-- 结构 -->
    <button>学习</button>
    <!-- 行为 -->
    <script>
    document.querySelector('button').onclick = function(){
        alert('学习:慢慢来')
    }
    </script>
</body>
</html>